1. Technical Field
The present invention relates to a PET industrial yarn melt direct spinning manufacturing method and its device, specifically belonging to the technical field of PET industrial yarn manufacturing.
2. Description of Related Art
Currently, PET industrial yarn manufacturing implements a chip spinning process where PTA and EG are submitted to esterification, pre-polycondensation, final-polycondensation and quenching, and then cut into chips having intrinsic viscosity of 0.63˜0.68 dL/g. The chips are further processed through solid-state polycondensation so as to produce high-viscosity chips of 0.85˜1.05 dL/g. The high-viscosity chips are put into a screw extruder for melt spinning. Finally, after drawing performed by heat rollers of multiple stages, the yarn is wound for formation. As mentioned herein, solid-state polycondensation refers to a process where polyester chips are submitted to polycondensation at a temperature that is 30° C.˜60° C. lower than the melting point thereof in a vacuum environment or in inert atmosphere such as that of nitrogen, so as to make the polyester's molecular weight continuously increase. The process of polycondensation can take as long as 20 some hours. The existing process for manufacturing PET industrial yarn through solid-state polycondensation chip spinning has problems such as long production cycles, large facility investment, and high energy consumption. Hence, liquid tackifying melt direct spinning manufacturing has been a desire in the industry.
Though there is technical breakthrough about liquid tackifying of polyester, two more technical problems have to be solved before large-scale melt direct spinning manufacturing of PET industrial yarn becomes possible. The first one is transportation of high-viscosity melt. PET industrial yarn requires melt having intrinsic viscosity of 0.90˜1.05 dL/g or even higher. Such high-viscosity melt has great kinematic viscosity, so it is necessary to properly arrange the piping transportation of the melt from liquid tackifying reactors to spinning boxes in order to prevent excessive viscosity drop and inconsistency.
The second problem is how to make the manufacturing flexible enough for multiple PET industrial yarns. For manufacturers, it is important to make melt direct spinning PET industrial yarns in a way that provides scale merit of polyester manufacturing and satisfies the market demand for multiple PET industrial yarns.